Insulator



Patented Oct. 24, 1933 1,931,626 I v INSULATOR '1 Frank J. Stevens, Vietnam/r, assign "to Locke Insulator Corporation; Baltimore, Md, a-corporationof Maryland No Drawing. Application December 7, 1925 I Serial No. 73,890 1 '9 Claims. .(01. 173 313) Elie-invention relates to insulators of that type having a hole therein for the reception of a pm.

u The principal object of the invention, generally 6 stated, is to provide a novel method of forming pin receiving holes in insulators.

It is well known that the ordinary method at present employed is to form the insulator with a threaded hole by means of a die or dies which 10 operate on the insulator, while it is still in a green or plastic condition, to form a threaded hole into which the pin may be subsequently screwed. A great difficulty has been that upon firing the insulators the resultant shrinkage is not necessarily uniform throughout a single piece or in different pieces and as a consequence the holes are frequently of different diameters in different pieces and out of true in the individual piece. In addition to being out of round, the

: taper of the hole, after firing, is frequently too great or too little for the proper reception of the pin.

To overcome the above mentioned difficulties expedients have been resorted to but with 111- different success as for instance it has been contemplated to cement a metal thimble of standard dimensions in a hole formed at the center of the insulator body or shell, but the use of such a thimble is almost prohibitive on account of the cost thereof and the cost of the labor involved.

It has also been attempted to produce the desired result by casting a lead thimble in a sanded pin hole, the casting being done about a mold which must of course be subsequently withdrawn, This latter mentioned method is impracticable for the reason that the lead comes in contact with the porcelain while in a molten condition and necessarily at such a high temperature that cracking of the porcelain of the insulator fre- 4 0 quently results.

The above facts have resulted in the present invention which has for its more specific object the provision of a method of forming a pin hole by means of a suitable cement cast about a prop- .45 er mold inserted within an ordinary hole formed insulator is formed with an ordinary hole while in aplastic "condition and is .of course' fired in' the usual manner. Thehole is :preferably, though diameter of the pin hole to be formed. A mold of suitable construction and mounting and operable by any desired means, but of course conforming to the particular type of pin to be used with the insulator, is then placed centrally within the hole and a proper cement is pouredor otherwise placed within the hole about the mold and permitted to set, after which the mold is withdrawn, leaving a threaded hole of true form and proper pitch capable of receivinga standard pin. Obviously, if the hole in the insulator body be sanded or otherwise roughened the holding action of the cement will be increased. In lieu of sanding or roughening, it is conceivable that the initial hole might be undercut, if preferred, or otherwise formed to insure adequate retaining means for the cement in which the pin hole is formed. In actual practice I have found that aluminate cement is highly satisfactory for the purpose. This particular variety of cement is put out by the Atlas Lumnite Cement Company under the trade name of Lumnite which was registered in the U. S. Patent Office as a trademark, the registrations being Nos. 192,958 and 261,704. Analysis of this cement discloses its ingredients to be as follows:

The advantage of using this particular substance is that it possesses certain characteristics as to smoothness, homogeneity and hardness as will render a pin hole therein as satisfactory as one in a thimble or bushing. Furthermore, the formation of a pin hole in this manner causes no strain whatsoever on the porcelain of the insulator and there is naturally no injury thereto.

While I have described the detailed operations involved in the method it should be understood that this is for illustrative purposes only as I reserve the right to make any such changes in the detailed steps involved and the particular material employed as do not constitute any departure from the spirit oi the invention or the scope oi. the claims hereunto appended.

Having thus described the invention, I claim:

1. An insulator comprising a porcelain body having. a hole therein, and a lining for the hole formed of aluminate cementitious material united tothewallottheholeandhavinganopening corresponding to a pin.

2. An insulator comprising a dielectric body having a cavity therein, and a filling within the cavity formed of aluminate cementitious material, said filling having a hole therein adapted to receive a pin.

3. An insulator having a hole therein lined with aluminate cement.

4. An insulator comprising a dielectric body having a cavity therein. a pin to be mounted within the cavity, and a mass of aluminate cementiillingthespace between the walloi the cavity and the pin.

aesnese 5. The insulator comprising a plurality of members held together by a cementitious mass of aluminate cement.

6. The insulator comprising at least one insulating component and a cementitious mass of aluminate cement associated therewith.

I. The insulator comprising members held in a predetermined relationship by a layer of material, said material comprising aluminate cement.

8. An insulator comprising a dielectric body, a metallic member, and a mass oi aluminate cement securing the metallic member to the dielectric body.

9. An insulator comprising a dielectric body, a metallic member, and means comprising aluminate cement for securing the body and metallic member to each other in predetermined spaced relation.

FRANK J. STEVENS. 

